There is known a system that uses a wireless transmission channel in part of a transmission channel to transmit/receive, for example, LAN (local area network) signals, which are standardized in IEEE802.3. In this type of system, a transmission device that is connected to a network device via a wired transmission channel transmits a LAN signal from the network device to an opposite opposing transmission device via a wireless transmission channel. The opposing transmission device outputs the signal received via the wireless transmission channel to the network device, which is connected to the opposing transmission device itself via the wired transmission channel.
Patent Document 1 discloses a method outlined below. That is to say, when a transmission device connected to the above system via the wireless transmission channel detects a failure in the transmission channel (the wired transmission channel and the wireless transmission channel connected to the transmission device), the network device connected to the station itself via the wired transmission channel is notified of the failure. Furthermore, the network device connected to the opposing transmission device via the wired transmission channel is also notified.
In this method, the transmission device cuts the wired transmission channel line connected to the transmission device when a failure in the transmission channel is detected. Furthermore, it converts a control signal sequence for notifying a failure into a data sequence and outputs the signal to the wireless transmission channel to thereby transmit the control signal sequence to the opposing transmission device. Moreover, the transmission device cuts the wired transmission channel of the station itself also when the control signal sequence is received from the opposing transmission device.
According to this method, the transmission device is capable of notifying a network device connected to the station itself of a failure when the transmission device detects a failure in the transmission channel. Furthermore, it is capable of notifying the network device connected to the station itself of a failure also when the opposing transmission device detects a failure in the transmission channel.
In recent years, transition to IP (Internet protocol) is progressing in networking. In systems such as the one mentioned above, the transmission device often houses a plurality of wired transmission channels and includes a switching function.
Patent Document 1 discloses a method in which also in a system with each transmission device housing a plurality of wired transmission channels therein, a failure is notified to each network device connected to the station itself and to each network device connected to the opposing station (FIG. 8 and paragraphs [0076] and [0077] in Patent Document 1).
In this method, each transmission device includes, for each of the plurality of wired transmission channels of the station itself, a function of detecting a failure in the wired transmission channel, a function of detecting a failure in the wireless transmission channel, and a function of outputting the control signal sequence mentioned above to the wireless transmission channel when a failure is detected. Each transmission device cuts the wired transmission channel when a failure is detected and when the control signal sequence is received from the opposing transmission device.
According to this method, also in the system with each transmission device housing a plurality of wired transmission channels therein, the transmission device is capable of notifying a network device connected to the station itself of a failure when the station itself detects a failure in the transmission channel. Furthermore, it is capable of notifying the network device connected to the station itself of a failure also when the opposing transmission device detects a failure in the transmission channel.
The method mentioned above is considered not limited to only being applied to a system that uses a wireless transmission channel in part of the transmission channel. That is to say, the method mentioned above is considered to be able to be applied also to a system in which transmission devices connected via a transmission channel (that corresponds to the above wireless transmission channel) between the transmission devices (that correspond to the above transmission devices) transmit signals of the plurality of wired transmission channels connected to the respective transmission devices.